JP2000133482A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a lighting failure caused by an instantaneous power failure and to restrain the increase of the size and the cost of a circuit. SOLUTION: This discharge lamp lighting device is provided with a discharge lamp DL, a D.C. power source 1 to obtain D.C. power from the A.C. power of the A.C. power source AC, a lighting circuit 4 composed of switching elements S41, S42, a detection circuit 8 for detecting voltage drop caused by the stop of power feeding from an A.C. power source AC, and a control circuit 7 having a power reducing part 9. When voltage drop is detected by the detection circuit 8, the power reducing part 9 directs the control circuit 7 to perform the on/off control of the switching elements S41, S42 for a predetermined period by the use of a control signal having an on-period shorter than that of a normal time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for lighting a discharge lamp using electric power obtained by turning on / off a switching element.

[0002]

2. Description of the Related Art FIG. 15 is a schematic structural view showing a conventional discharge lamp lighting device. This discharge lamp lighting device is composed of a discharge lamp DL and a rectifier DB which takes in AC power from an AC power supply AC and performs rectification. DC power supply PA1 and inductor L2
1, a boost chopper circuit PA2 composed of an FET Q21, a diode D21 and a capacitor C21;
TQ31, diode D31, primary and secondary winding n3
1, a step-down chopper circuit PA3 including a transformer CT having n32, a resistor R31 and a capacitor C31.
And switching elements S41 to S44, diode D4
1 to D44, a lighting circuit PA4 including a pulse transformer PT having primary and secondary windings n1 and n2, and an igniter 40 for generating a high-voltage pulse voltage for starting a discharge lamp, and an output voltage of a step-up chopper circuit PA2. (A voltage across the capacitor C21), a control circuit PA5 for performing on / off control of the switching element Q21 such that the detection result maintains a set level higher than the output voltage level of the rectifier DB, and a step-down chopper. F of circuit PA3
A control circuit PA6 for controlling the supply of predetermined power from the step-down chopper circuit PA3 to the lighting circuit PA4 by the on-duty control of the ETQ31, and a power whose current becomes a substantially square wave of several hundred Hz by the on / off control of the switching elements S41 to S44. And a control circuit PA7 for controlling the supply from the lighting circuit PA4 to the discharge lamp DL. However, capacitor C
31 and the secondary winding n2 of the pulse transformer PT constitute a low-pass filter for reducing the high-frequency component of the current flowing through the discharge lamp DL.

[0003] In the discharge lamp lighting device configured as described above, when an HID lamp or the like is used as the discharge lamp DL, the capacity of the capacitor C21 is selected in order to cope with an instantaneous power failure (instantaneous power failure) of the AC power supply AC. Is performed. That is, in the case of the HID lamp, if it goes out, it takes several minutes to several tens of minutes to restart.
In order to prevent the disappearance due to the instantaneous power failure, the capacity of the capacitor C21 is selected so that power can be supplied even during the instantaneous power failure. Thus, by selecting the capacity of the capacitor C21, it is possible to prevent the discharge lamp DL from going out even if an instantaneous power failure of the AC power supply AC occurs.

In some cases, an instant restart type igniter is mounted on a discharge lamp lighting device. In this case, the discharge lamp DL goes out due to an instantaneous power failure of the AC power supply AC, and thereafter, when the AC power supply AC is restored, the igniter applies a high voltage pulse voltage several times higher than usual to the discharge lamp DL.
This enables instantaneous restart of the discharge lamp DL.

[0005]

However, the disappearance due to the momentary power failure of the AC power supply AC is prevented by the capacitor C21.
In the method of preventing by selecting the capacitance of the capacitor C21,
Becomes very large, which results in an increase in the size of the circuit and an increase in cost.

On the other hand, in the method of mounting the igniter of the instantaneous restart type, it is not necessary to use a capacitor having a very large capacity as the capacitor C21. However, as described above, the size of the igniter circuit is increased and the cost is increased. Become.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a discharge lamp lighting device capable of preventing extinction due to an instantaneous power failure, suppressing an increase in circuit size, and suppressing an increase in cost. And

[0008]

According to a first aspect of the present invention, there is provided a discharge lamp lighting apparatus comprising: a discharge lamp; a DC power supply comprising a rectifier for rectifying AC power from an AC power supply; a switching element; A lighting circuit comprising an inductance element for supplying power to the discharge lamp using power from the DC power supply, detection means for detecting a voltage drop due to stop of power supply from the AC power supply, and voltage detection by the detection means When a drop is detected, a power reduction unit that performs control for reducing the amount of power supplied to the discharge lamp for a predetermined time is provided.

According to this configuration, the extinction due to an instantaneous power failure is prevented, and an increase in the size and cost of the circuit is suppressed.

[0010] It is also possible to employ a configuration comprising a switching element and an inductance element, and a chopper circuit for converting the voltage level from the rectifier to a predetermined level and supplying DC power to the lighting circuit side. Also in this configuration, extinction due to an instantaneous power failure is prevented, and an increase in circuit size and cost are suppressed.

Further, the power reduction means may be configured to perform, for a predetermined time, the supply control of the DC power of which power supply amount is reduced to the discharge lamp when a voltage drop is detected by the detection means. Also in this configuration, extinction due to an instantaneous power failure is prevented, and an increase in circuit size and cost are suppressed.

An igniter for generating a high voltage for starting the discharge lamp is provided, and the power reduction means performs a high voltage generation control of the igniter for a predetermined time when a voltage drop is detected by the detection means. May be. Also in this configuration, extinction due to an instantaneous power failure is prevented, and an increase in circuit size and cost are suppressed.

The power reduction means may be configured to stabilize the discharge lamp by glow discharge for a predetermined time when a voltage drop is detected by the detection means. Also in this configuration, extinction due to an instantaneous power failure is prevented, and an increase in circuit size and cost are suppressed.

In addition, the apparatus further comprises a current detecting means for detecting a current flowing through the discharge lamp, wherein the power reducing means, when a voltage drop is detected by the detecting means, is obtained from a detection result of the current detecting means. A configuration may be adopted in which the discharge lamp is supplied with power at which the value of the lamp current of the discharge lamp is equal to or less than a current value capable of shifting to arc discharge, and the discharge of the discharge lamp is changed to glow discharge. Also in this configuration, extinction due to an instantaneous power failure is prevented, and an increase in circuit size and cost are suppressed.

Further, the power reduction means may be configured to make the lamp current at the time of glow discharge constant. Even with this configuration,
Disappearance due to an instantaneous power failure is prevented, and an increase in circuit size and cost are suppressed.

Further, the discharge lamp may be changed from a glow discharge to an arc discharge after the predetermined time has elapsed. Also in this configuration, extinction due to an instantaneous power failure is prevented, and an increase in circuit size and cost are suppressed.

Furthermore, the lamp has a voltage application capability not less than a maximum value of a lamp voltage generated at the time of transition between glow discharge and arc discharge, and after the predetermined time has elapsed, the discharge of the discharge lamp is shifted to arc discharge. The discharge lamp may be supplied with electric power having a current value equal to or greater than a possible current value, and the discharge lamp may be changed from a glow discharge to an arc discharge. Also in this configuration, extinction due to an instantaneous power failure is prevented, and an increase in circuit size and cost are suppressed.

[0018]

FIG. 1 is a schematic configuration diagram of a discharge lamp lighting device according to a first embodiment of the present invention, FIG. 2 is a circuit diagram of a detection circuit shown in FIG. 1, and FIG. 3 is a control circuit shown in FIG. In the explanatory diagram of
Hereinafter, the first embodiment will be described with reference to these drawings.

As shown in FIG. 1, this discharge lamp lighting device includes a discharge lamp (for example, an HID lamp) DL, an AC power supply AC.
A DC power supply 1 for obtaining DC power from AC power and a lighting circuit 4 including switching elements S41 and S42 are provided in the same manner as in the related art, and a feature of the first embodiment is that a detection circuit (detection means) 8 and a control circuit 7 to which a power reduction unit (power reduction means) 9 is added.

The respective components of the discharge lamp lighting device thus configured will be described in more detail. The DC power supply 1 receives rectified AC power from an AC power supply AC and rectifies it. It is composed of connected capacitors C11 and C12 connected in series. However, in the example of FIG. 1, the capacitor C11 is connected to the high potential side output terminal of the rectifier DB.

The lighting circuit 4 includes capacitors C11 and C12.
Series-connected switching element S41,
S42, diodes D41 and D42 connected in parallel with these switching elements S41 and S42, an igniter 40 for generating a high-voltage pulse for starting the discharge lamp, and a pulse transformer PT.

The pulse transformer PT includes an igniter 4
0, the primary winding n1 connected between both output terminals, the connection point of the capacitors C11 and C12, and the switching element S4
1 and a secondary winding n2 connected between the connection point of S42 and one end connected to the connection point of the capacitors C11 and C12.

The switching elements S41 and S42 may be transistors or FETs.
For example, in the case of an FET, an FET Q4 shown in FIG.
1, Q42, if a source (substrate) is connected and a body (parasitic) diode in which a cathode and an anode are respectively connected to a drain and a source is generated, such a parasitic diode is a diode D41, D42, the diode D41,
It is not necessary to separately provide D42.

As shown in FIG. 2, the detection circuit 8 includes a series-connected resistor R81, connected between both output terminals of the rectifier DB.
R82, a comparator 80 having a non-inverting input terminal connected to the connection point of the resistors R81 and R82 and an inverting input terminal to which a predetermined reference voltage Vref is applied. In this configuration, the output of the comparator 80 as the output of the detection circuit 8 is the output voltage of the rectifier DB,
That is, when the voltage between both ends of the resistor R82 becomes lower than the reference voltage Vref, it becomes L level, and when it becomes higher, it becomes H level. As a result, when the AC power supply AC is momentarily interrupted, that is, when the supply of power from the AC power supply AC is stopped, the output voltage of the rectifier DB drops, and the voltage across the resistor R82 becomes lower than the reference voltage Vref. Changes from the H level to the L level, it is possible to detect a voltage drop due to an instantaneous power failure of the AC power supply AC.

Normally, the control circuit 7 sends a control signal as shown in FIG. 3A to the switching elements S41 and S42 in order to convert the DC power from the DC power supply 1 into AC power. In addition to having the same function as the conventional one for performing on / off control of S41 and S42,
A function of the power reduction unit 9 is further provided.

The power reduction unit 9 controls the on / off control of the switching elements S41 and S42 as shown in FIG. 3B when the voltage drop is detected by the detection circuit 8, as shown in FIG. 3B. Is performed for a predetermined time by a control signal having an ON period shorter than that of the normal time. As a result, when the voltage drop is detected by the detection circuit 8, the control circuit 7 performs the control for reducing the power supply amount to the discharge lamp DL for a predetermined time. Then, the predetermined time can be set longer by the reduced amount.
In the example of FIG. 3B, the ON period is significantly shorter than the ON period of FIG.

Therefore, the control circuit 7 normally operates
In order to convert the DC power from the DC power supply 1 into AC power, the switching element S4 is controlled by a control signal as shown in FIG.
1, while ON / OFF control of S42 is performed, and when the voltage drop is detected by the detection circuit 8, the discharge lamp DL
In order to execute the control for reducing the amount of power supplied to the
The switching element S4 is controlled by a control signal as shown in FIG.
1, on / off control of S42 is performed.

However, in the first embodiment, the control circuit 7 turns on / off the switching elements S41 and S42.
In the off control, a period in which the switching element S42 is off and the switching element S41 is on / off, and a period in which the switching element S41 is off and the switching element S42 is on / off are switched at about several hundred Hz. The on / off of the switching element in each period is switched at about several tens of kHz.

Next, the operation of the first embodiment will be briefly described. For example, when the switching element S42 is off and the switching element S41 is on / off, the capacitor C
As the battery 12 is charged, AC power whose current becomes a substantially rectangular wave of several hundred Hz is supplied to the discharge lamp DL. Next, when the switching element S41 is turned off and the switching element S42 is turned on / off, the capacitor C11 is charged, and the AC power whose current is a substantially rectangular wave of several hundred Hz is supplied to the discharge lamp DL. Thereafter, the series of on / off control is repeatedly executed. By such normal ON / OFF control, the discharge lamp DL shifts from the starting state to the lighting state, and this lighting state is maintained until the power is turned off.

However, if the AC power supply AC causes an instantaneous power failure due to some cause different from the power-off (for example, the cause of the AC power supply AC itself or another cause such as the AC power supply AC itself being normal and poor contact), A voltage drop caused by the instantaneous power failure of the AC power supply AC is detected, and the switching elements S41 and S41 are turned on by a control signal having a shorter on-period than in a normal state.
42 is turned on / off for a predetermined time. Thereby, the discharge lamp D
L is in the dimming state. Further, the amount of power supply to the discharge lamp DL is reduced, and the amount of charge power of the capacitors C11 and C12 is reduced.

Thereafter, when the AC power supply AC recovers from the instantaneous power failure and the above-mentioned predetermined time elapses, the switching elements S41 and S42 are turned on / off by the normal control signal. As a result, the discharge lamp DL quickly returns from the dimming state to the lighting state without extinguishing.

As described above, according to the first embodiment, it is possible to prevent extinguishing due to an instantaneous power failure. Further, since it is not necessary to increase the capacitance of the capacitors C11 and C12 and it is not necessary to make the igniter 40 an instantaneous restart type, it is possible to suppress an increase in circuit size. Thereby, cost increase can be suppressed.

FIG. 4 is a schematic configuration diagram of a discharge lamp lighting device according to a second embodiment of the present invention, and the second embodiment will be described below with reference to FIG.

This discharge lamp lighting device includes a discharge lamp DL, a DC power supply 1a for obtaining DC power from AC power of an AC power supply AC,
The step-up chopper circuit 2 constituted by the FET Q21 and the like, the step-down chopper circuit 3 constituted by the FET Q31 and the like, the lighting circuit 4a constituted by the switching elements S41 to S44, and the like,
Control circuit 5 for performing off control, and switching element S
The lighting circuit 4a is controlled by turning on / off 41 to S44.
A control circuit 7a for controlling the power supply to the discharge lamp DL from the control circuit 7a is provided in the same manner as in the prior art. Is provided with a control circuit 6. However, the block division in FIG. 4 is for convenience of explanation, and, for example, the DC power supply 1a and the boost chopper circuit 2 are divided into blocks, but the step-up chopper circuit 2 may be divided into blocks included in the DC power supply 1a. .

The respective parts of the discharge lamp lighting device configured as described above will be further described. The DC power supply 1a is a rectifier D that takes in AC power from an AC power supply AC and performs rectification.
B.

The boost chopper circuit 2 has an inductor L21 connected to one end of the high potential side output terminal of the rectifier DB and one end thereof, and a drain and a source connected to the other end of the inductor L21 and the low potential side output terminal of the rectifier DB. FE
It comprises a TQ21, a diode D21 connected to the other end of the inductor L21 and the anode, and a capacitor C21 connected between the cathode of the diode D21 and the low potential output terminal of the rectifier DB.

The step-down chopper circuit 3 includes a diode D21
Q31 having a cathode and a drain connected to each other, a diode D31 having a source connected to the source of the FET Q31 and a low potential output terminal of the rectifier DB and a cathode and an anode, an inductor L31 having one end connected to the source of the FET Q31, and It is constituted by a capacitor C31 connected between the other end of the inductor L31 and the low potential output terminal of the rectifier DB.

The lighting circuit 4a comprises switching elements S41, S4 connected in series with the capacitor C31 in series.
2. Diodes D41 and D42 connected in parallel with these switching elements S41 and S42, switching elements S43 and S44 connected in series with switching elements S41 and S42, and connected in parallel with these switching elements S43 and S44, respectively. Diode D
43, D44, an igniter 40, and a pulse transformer PT. This pulse transformer PT
Is a primary winding n1 connected between both output terminals of the igniter 40, and is connected between a connection point between the switching elements S41 and S42 and a connection point between the switching elements S43 and S44, and has one end connected to the switching elements S41 and S42. And a secondary winding n2 connected to the connection point. The switching elements S41 to S44 may be transistors or FETs as in the first embodiment.

The control circuit 5 detects the output voltage level of the boost chopper circuit 2, and controls the on / off control of the switching element Q21 so that the detection result maintains a set level higher than the output voltage level of the rectifier DB. Is what you do.

The control circuit 7a includes a switching element S4
1 and S44 and on / off control of each set of the switching elements S42 and S43 are alternately repeated at about several hundred Hz.

The detection circuit 8a detects, for example, an AC voltage or a draw current of the AC power supply AC, and detects a voltage drop caused by an instantaneous power failure of the AC power supply AC when the AC voltage or the draw current is no longer detected. It is.

The control circuit 6 normally has the same function as that of the related art for controlling the supply of a predetermined DC power from the step-down chopper circuit 3 to the lighting circuit 4a by the on-duty control of the FET Q31 of the step-down chopper circuit 3. In addition, a function of the power reduction unit 9a is further provided. However,
The FET Q31 is configured to operate at about several tens of kHz.

The power reduction section 9a controls the FET Q31 for a predetermined time by an on-duty control signal having a short on-period when a voltage drop is detected by the detection circuit 8a. This allows
When the voltage drop is detected by the detection circuit 8a, the control circuit 6 controls the power supply from the step-down chopper circuit 3 to the lighting circuit 4a for a predetermined time. The on-duty control signal having a short on-period may be, for example, an on-duty control signal having a shortest on-period in a normal state, or an on-duty control signal having a shorter on-period.

Therefore, the control circuit 6 normally operates
While the supply control of the predetermined DC power from the step-down chopper circuit 3 to the lighting circuit 4a is performed by the on-duty control of the FET Q31, the voltage supply amount to the discharge lamp DL is detected when the voltage drop is detected by the detection circuit 8a. In order to execute the reduction control for a predetermined time, the FET Q31 is controlled for a predetermined time by an on-duty control signal having a short ON period.

Next, the characteristic operation of the second embodiment performed in accordance with the detection result of the detection circuit 8a will be described.
Is performed, and a predetermined DC power is supplied from the step-down chopper circuit 3 to the lighting circuit 4a. The DC power is converted into AC power suitable for starting or lighting by the lighting circuit 4a by on / off control of the control circuit 7a and supplied to the discharge lamp DL. As a result, the discharge lamp DL shifts from the starting state to the lighting state, and this lighting state is maintained until the power is turned off.

However, if the AC power supply AC causes an instantaneous power failure for some reason different from the power-off, a voltage drop due to the instantaneous power failure of the AC power supply AC is detected.
The FET Q is controlled by an on-duty control signal with a short on-period.
31 is turned on / off for a predetermined time. Thereby, the discharge lamp D
L is in the dimming state, the amount of power supplied to the discharge lamp DL is reduced, and the amount of power used for charging the capacitor C21 is reduced.

Thereafter, the AC power supply AC recovers from the instantaneous power failure, and when the above-mentioned predetermined time elapses, the normal on-duty control of the FET Q31 is performed, and the predetermined DC power is supplied from the step-down chopper circuit 3 to the lighting circuit 4a. You. This DC power is converted into AC power suitable for lighting by the lighting circuit 4a by on / off control of the control circuit 7a and supplied to the discharge lamp DL. Thus, the discharge lamp DL immediately returns from the dimming state to the lighting state without extinguishing.

As described above, according to the second embodiment, it is possible to prevent extinguishing due to an instantaneous power failure. Further, since it is not necessary to increase the capacity of the capacitor C21 and it is not necessary to make the igniter 40 an instantaneous restart type, it is possible to suppress an increase in the size of the circuit. Thereby, cost increase can be suppressed.

FIG. 5 is a schematic configuration diagram of a discharge lamp lighting device according to a third embodiment of the present invention, and FIG. 6 is an explanatory diagram of a control circuit for the lighting circuit shown in FIG. Three embodiments will be described.

This discharge lamp lighting device includes a DC power supply 1a, a step-up chopper circuit 2, a lighting circuit 4a, and a control circuit 5 in the same manner as in the second embodiment. In addition, a step-down chopper circuit 3a, a control circuit 6a and a control circuit 7b are provided.

The step-down chopper circuit 3a includes a diode D2
The FET Q31 has its cathode and drain connected, the source of the FET Q31 and the low-potential output terminal of the rectifier DB are connected to the cathode and anode, respectively, the diode D31, the primary winding n31 having one end connected to the source of the FET Q31 and Transformer C having a secondary winding n32 to which one end of the rectifier DB is connected to one output terminal on the low potential side
T, a capacitor C31 connected between the other end of the primary winding n31 and the low-potential output terminal of the rectifier DB, and a resistor R31 connected to the other end of the secondary winding n32 and one end. .

The control circuit 6a has a configuration in which the output current of the step-down chopper circuit 3a is detected from the other end of the resistor R31, and a power reduction section 9a is added similarly to the second embodiment. I have.

The control circuit 7b is normally operated by the control circuit 7b.
In addition to having a function that operates in the same way as a, a function by a power reduction unit (power reduction means) 9b is further provided.

The power reduction section 9b performs control for keeping the switching elements S41 and S44 (or S42 and S43) on for a predetermined time when a voltage drop is detected by the detection circuit 8 when a voltage drop is detected. As a result, the discharge lamp DL is substantially DC-lit by DC power supply with a constant current and voltage, as shown in the period of the instantaneous power failure in FIG.

Next, the operation of the third embodiment, which is performed in accordance with the detection result of the detection circuit 8, will be described.
1 is performed, and the step-down chopper circuit 3
A predetermined DC power is supplied from a to the lighting circuit 4a. This DC power is converted into AC power suitable for starting or lighting by the lighting circuit 4a by on / off control of the control circuit 7b and supplied to the discharge lamp DL. Thereby, the discharge lamp DL
Shifts from the starting state to the lighting state, and this lighting state is maintained until the power is turned off.

However, if the AC power supply AC experiences an instantaneous power failure for some reason different from the power cut-off, a voltage drop due to the instantaneous power failure of the AC power supply AC is detected.
For example, the switching elements S41 and S44 are turned on for a predetermined time, and the FET Q31 is turned on / off by an on-duty control signal having a short on-period. At this time, as shown in the period of the momentary power failure in FIG. 6, the discharge lamp DL is supplied by the supply of the DC power at which the lamp voltage V _DL and the lamp current I _DL are constant.
In the dimming state, the amount of power supply to the discharge lamp DL is reduced, and the amount of power used for charging the capacitor C21 is reduced. Further, since the re-ignition voltage at the time of dimming can be suppressed, the extinction resistance can be improved, and a deeper dimming state can be achieved. This makes it possible to further reduce the amount of power used for charging the capacitor C21, and to set the predetermined time longer.

Thereafter, the AC power supply AC recovers from the instantaneous power failure, and when the above-mentioned predetermined time has elapsed, normal on-duty control of the FET Q31 is performed, and predetermined DC power is supplied from the step-down chopper circuit 3a to the lighting circuit 4a. You. This DC power is converted into AC power suitable for lighting in the lighting circuit 4a by on / off control of the control circuit 7b, and the discharge lamp DL
Supplied to Thus, the discharge lamp DL immediately returns from the dimming state to the lighting state without extinguishing.

As described above, according to the third embodiment, it is possible to prevent extinguishing due to an instantaneous power failure. Further, since it is not necessary to increase the capacity of the capacitor C21 and it is not necessary to make the igniter 40 an instantaneous restart type, it is possible to suppress an increase in the size of the circuit. Thereby, cost increase can be suppressed.

In the third embodiment, the power reduction unit 9
Both a and 9b are configured to operate for a predetermined time when the voltage drop is detected by the detection circuit 8, but are not limited thereto, and may be configured to operate during the period when the voltage drop is detected by the detection circuit 8. Good. Even in this latter configuration, it goes without saying that the above-described effects can be obtained if the power supply from the AC power supply AC is momentarily stopped for some reason. However, in this case, both the power reduction units 9a and 9b need to be configured to stop operating when the voltage drop is no longer detected by the detection circuit 8. This is the same in other embodiments.

FIG. 7 is a schematic configuration diagram of a discharge lamp lighting device according to a fourth embodiment of the present invention. The fourth embodiment will be described below with reference to FIG.

This discharge lamp lighting device includes a DC power supply 1a, a step-up chopper circuit 2, a step-down chopper circuit 3a, control circuits 5, 6a, and a detection circuit 8 in the same manner as the third embodiment. A lighting circuit 4c is provided in addition to the control circuit 7a similar to the above.

The lighting circuit 4c includes a switching element S
41 to S44, diodes D41 to D44, and a pulse transformer PT are provided in the same circuit arrangement as the lighting circuit 4a, and in place of the igniter 40, an igniter 40a to which a power reduction unit (power reduction means) 9c is added is provided. I have.

The igniter 40a has a function similar to the conventional one for generating a high-voltage pulse voltage when the discharge lamp is started, and further has a function of the power reduction unit 9c.

The power reduction section 9c generates a high-voltage pulse voltage for a predetermined time when the voltage drop is detected by the detection circuit 8. Accordingly, the igniter 40a generates a high-voltage pulse voltage when the discharge lamp is started, and generates a high-voltage pulse voltage for a predetermined time when a voltage drop is detected by the detection circuit 8.

Next, the characteristic operation of the fourth embodiment performed according to the detection result of the detection circuit 8 will be described. Normally, the normal on-duty control of the FET Q31 is performed and the step-down chopper circuit 3a turns on the light. Circuit 4c
Is supplied with a predetermined DC power. This DC power is converted into AC power suitable for starting or lighting by the lighting circuit 4c by on / off control of the control circuit 7a and supplied to the discharge lamp DL. As a result, the discharge lamp DL shifts from the starting state to the lighting state, and this lighting state is maintained until the power is turned off.

However, if the AC power supply AC causes an instantaneous power failure for some reason different from the power-off, a voltage drop due to the instantaneous power failure of the AC power supply AC is detected.
The FET Q is controlled by an on-duty control signal with a short on-period.
While 31 turns on / off for a predetermined time, a high-voltage pulse voltage is applied to the discharge lamp DL from the igniter 40a via the pulse transformer PT. As a result, the discharge lamp DL enters the dimming state, the amount of power supplied to the discharge lamp DL is reduced, and the amount of charge power of the capacitor C21 is reduced.

[0067] indicates the state of the lamp voltage V _DL and the lamp current I _DL of the discharge lamp DL in this case during the "instantaneous power outage" in FIG. As described above, by applying the pulse voltage, the discharge lamp DL can be brought into a deeper dimming state, and the amount of charge power of the capacitor C21 can be further reduced. As a result, the predetermined time can be set longer.

Thereafter, the AC power supply AC recovers from the instantaneous power failure, and when the above-mentioned predetermined time elapses, the normal on-duty control of the FET Q31 is performed, and the predetermined DC power is supplied from the step-down chopper circuit 3a to the lighting circuit 4c. You. This DC power is converted into AC power suitable for lighting by the lighting circuit 4c by ON / OFF control of the control circuit 7a, and the discharge lamp DL
Supplied to Thus, the discharge lamp DL immediately returns from the dimming state to the lighting state without extinguishing.

As described above, according to the fourth embodiment, it is possible to prevent extinguishing due to an instantaneous power failure. Further, it is not necessary to increase the capacity of the capacitor C21, and it is not necessary to make the igniter 40a an instantaneous restart type, so that it is possible to suppress an increase in circuit size. Thereby, cost increase can be suppressed.

FIG. 9 is a schematic configuration diagram of a discharge lamp lighting device according to a fifth embodiment of the present invention. The fifth embodiment will be described below with reference to FIG.

This discharge lamp lighting device comprises a rectifier D which takes in AC power from a discharge lamp DL and an AC power supply AC and performs rectification.
DC power supply 1 including B and a smoothing capacitor (not shown)
b, a DC power supply 1b including at least a switching element (FET in FIG. 9) S and an inductance element L
Circuit 4d for supplying electric power to the discharge lamp DL using electric power from the lighting circuit 4d.
A detection unit 8b for detecting a voltage drop due to a stop of power supply from the power supply and a lighting circuit 4d. When the voltage drop is detected by the detection unit 8b, the power for discharging the discharge lamp DL to a glow discharge for a predetermined time Reduction unit (power reduction means) 9
d.

[0072] Here, the discharge lamp DL, the relationship between the lamp voltage V _DL and the lamp current I _DL as shown in FIG. 10, are mainly classified into glow discharge and arc discharge. The discharge lamp lighting device normally _{supplies the} electric power that becomes the lamp voltage V _DL and the lamp current I _DL at point C shown in FIG.
L, and the discharge lamp DL is set to be stably lit and maintained by the arc discharge at the point C.

[0073] The power reduction unit 9d, at the time of the step-down detection voltage drop is detected by the detection unit 8b is the lamp voltage V _DL and the lamp current I _DL become power discharge lamp DL at the point A shown in FIG. 10 for example To be supplied.

[0074] Thus, the lighting circuit 4d is in the normal, while supplying power to the lamp voltage V _DL and the lamp current I _DL at the point C to the discharge lamp DL, during the step-down detection voltage drop by the detector 8b is detected , A, the lamp voltage V _DL and the lamp current I _DL are supplied to the discharge lamp DL for a predetermined time.

Next, the characteristic operation of the fifth embodiment performed according to the detection result of the detection unit 8b will be described. Normally, for example, the power at which the lamp voltage V _DL and the lamp current I _DL at the point C are obtained. Is supplied to the discharge lamp DL.
Thus, the discharge lamp DL is stably lit by the arc discharge at the point C, and this lit state is maintained until the power is turned off.

However, if the AC power supply AC causes an instantaneous power failure for any reason different from the power-off, a voltage drop due to the instantaneous power failure of the AC power supply AC is detected.
For example power the lamp voltage V _DL and the lamp current I _DL at the point A is supplied for a predetermined time to the discharge lamp DL. As a result, the discharge lamp DL maintains stable lighting by the glow discharge at the point A. At this time, the electric energy supplied to the discharge lamp DL is smaller than the electric energy at the point C.

Thereafter, the AC power supply AC recovers from the momentary power failure, and when the predetermined time elapses, the lamp voltage V at point C
Power the _DL and the lamp current I _DL is supplied to the discharge lamp DL. As a result, the discharge lamp DL quickly returns from the glow discharge state at the point A to the arc discharge state at the point C.

As described above, according to the fifth embodiment, it is possible to prevent extinguishing due to an instantaneous power failure. When a voltage drop is detected by the detection unit 8b, the discharge lamp DL
Since the amount of power supplied to the igniter is reduced, it is not necessary to increase the capacity of the smoothing capacitor, and even if the igniter is used, it is not necessary to make the igniter an instantaneous restart type. It becomes possible to suppress. Thereby, cost increase can be suppressed.

FIG. 11 is a schematic configuration diagram of a discharge lamp lighting device according to a sixth embodiment of the present invention. Hereinafter, the sixth embodiment will be described with reference to FIG.

This discharge lamp lighting device includes a discharge lamp DL and a DC power supply 1b as in the fifth embodiment.
A lighting circuit 4e that includes at least a switching element S and an inductance element L and supplies power to the discharge lamp DL using power from the DC power supply 1b, and a detection circuit 8 provided in the lighting circuit 4e and according to the fifth embodiment. A similar detection unit 8b, a current detection circuit (current detection unit) 10 for detecting a current value flowing through the discharge lamp DL, and a power reduction unit (power reduction unit) 9e provided in the lighting circuit 4e are provided.

[0081] The power reduction portion 9e, when the voltage drop is detected by the detecting unit 8b, a current value detected by the current detection circuit 10 is migratable current I _G following example point A to arc discharge lamps The electric power to be a current is supplied to the discharge lamp DL for a predetermined time so that the discharge state of the discharge lamp DL is stabilized by glow discharge. However, the current value I
_G means the lamp current at the time when the lamp voltage generated between the normal glow discharge and the arc discharge reaches a maximum as shown in FIG.

Next, the characteristic operation of the sixth embodiment performed in accordance with the detection result of the detection unit 8b will be described. Normally, for example, the lamp voltage V at point C in FIG.
Power the _DL and the lamp current I _DL is supplied to the discharge lamp DL. Thus, the discharge lamp DL is stably lit by the arc discharge at the point C, and this lit state is maintained until the power is turned off.

However, if an instantaneous power failure occurs in the AC power supply AC for some reason different from the power-off, a voltage drop due to the instantaneous power failure of the AC power supply AC is detected. When this voltage drop is detected, the current value detected by the current detection circuit 10 is the power to be the lamp current of the following example point A current I _G is supplied for a predetermined time to the discharge lamp DL. As a result, the discharge lamp DL maintains stable lighting by the glow discharge at the point A. At this time, the electric energy supplied to the discharge lamp DL is smaller than the electric energy at the point C.

Thereafter, the AC power supply AC recovers from the momentary power failure, and when the predetermined time elapses, the lamp voltage V at point C
Power the _DL and the lamp current I _DL is supplied to the discharge lamp DL. As a result, the discharge lamp DL quickly returns from the glow discharge state at the point A to the arc discharge state at the point C.

As described above, according to the sixth embodiment, the same effects as those of the fifth embodiment can be obtained.

In the sixth embodiment, the power reduction unit 9e
When the voltage drop is detected, has a power current value detected by the current detection circuit 10 is composed of a lamp current of the following example point A current I _G to the discharge lamp DL to the structure to supply a predetermined time but not limited thereto, and may be configured to provide a predetermined time power current value detected by the current detection circuit 10 is composed of a lamp current of the following example the point D current I _G to the discharge lamp DL. In short, the power reduction means of the present invention
The current value detected by the current detection circuit 10 is a current value I _G
Any configuration may be used as long as the following power is supplied to the discharge lamp DL for a predetermined time.

FIG. 12 is a schematic configuration diagram of a discharge lamp lighting device according to a seventh embodiment of the present invention, and FIG. 13 is an explanatory diagram of a control circuit shown in FIG. 12. Hereinafter, the seventh embodiment will be described with reference to these drawings. explain.

This discharge lamp lighting device includes a DC power supply 1a and a step-down chopper circuit 3, similarly to the second embodiment, and further includes a step-up chopper circuit 2a, a lighting circuit 4f, and a control circuit CC1.

The boost chopper circuit 2a includes an inductor L2
1, an FET Q21, a diode D21, and a capacitor C21 in the same circuit arrangement as the second embodiment, and a capacitor C connected between both output terminals of the rectifier DB.
22 is further provided.

The lighting circuit 4f connects the switching elements S41 to S44 and the diodes D41 to D44 in the lighting circuit 4a of the second embodiment to the FETs Q41 to Q44.
It consists of.

The control circuit CC1 controls the entire discharge lamp lighting device. For example, as shown by V _C21 (output voltage of the step-up chopper circuit 2a) in FIG. When starting the electric light DL (when not lit in FIG. 13)
The output voltage level of the step-up chopper circuit 2a is detected regardless of whether it is lit or not, and the ON / OFF control of the FET Q21 is performed so that the detection result maintains a set level higher than the output voltage level of the rectifier DB.

The control circuit CC1 is connected to V3 in FIG.
As shown in (output voltage of step-down chopper circuit 3), at the time of starting, on / off control of FET Q31 is performed so that the level of output voltage V3 is at the level of voltage Va. On / off control of the FET Q31 is performed so that the level of the voltage Vb is lower than the voltage Va.

The control circuit CC1 includes FETs Q41 and Q41.
On / off control of each set of the FET 44 and the FETs Q42 and Q43 is alternately repeated to control the predetermined DC power from the step-down chopper circuit 3 to be converted into AC power by the lighting circuit 4f. As a result, a rectangular wave AC voltage as shown by the lamp voltage _VDL in FIG. 13 is applied to the discharge lamp DL. In particular, at the time of lighting, the discharge of the discharge lamp DL is as shown in FIG.
Is controlled to convert the DC power from the step-down chopper circuit 3 into the AC power so that the arc discharge is determined by the lamp voltage and the lamp current at the point C, for example.

Further, at the time of starting, the control circuit CC1 controls the igniter 40 to apply a high-voltage pulse voltage as shown by the lamp voltage _VDL in FIG. 13 to the discharge lamp DL.

Further, the control circuit CC1 includes a detection section (detection means) 8b constituted by, for example, the same circuit as that shown in FIG. 2, and this detection section 8b detects a voltage drop due to an instantaneous power failure of the AC power supply AC. .

Further, the control circuit CC1 includes a power reduction section 9f.
When a voltage drop is detected by the detection unit 8b, the power reduction unit 9f converts AC power at which the discharge of the discharge lamp DL becomes glow discharge determined by, for example, the lamp voltage and lamp current at point A shown in FIG. From the lighting circuit 4f to the discharge lamp DL
The ON / OFF control of the FETs Q41 to Q44 is performed for a predetermined period of time so that the power is supplied to the FETs Q41 to Q44. That is, the control circuit CC1
Control is performed to switch on / off control of the FETs Q41 to Q44 between glow discharge and arc discharge in accordance with whether or not a voltage drop is detected by the detection unit 8b.

Next, the operation of the seventh embodiment will be described. When the power is turned on, the discharge lamp lighting device enters a start state, and the control circuit CC1 operates to perform output control of each voltage and power supply control to the discharge lamp DL during non-lighting shown in FIG. Will be

That is, the output voltage level of the boost chopper circuit 2a is detected, and the on / off control of the FET Q21 is controlled so that the detection result maintains a set level higher than the output voltage level of the rectifier DB. Is performed. As a result, the output voltage of the boost chopper circuit 2a becomes
A voltage V _C21 shown in FIG. 13 is obtained.

The output voltage level of the step-down chopper circuit 3 is detected.
The on / off control of the FET Q31 is performed so that the voltage Va shown in FIG.

Further, for the lighting circuit 4f, an FET
Q41~Q44 ON / OFF control is performed, the output voltage of the step-down chopper circuit 3 is applied to be converted into a rectangular wave AC voltage as shown in V _DL discharge lamp DL in FIG. At this time, the output control of the igniter 40 is also performed, and the step-down pulse voltage is superimposed on the rectangular wave AC voltage.

Thereafter, when the discharge lamp DL is insulated and the present discharge lamp lighting device is turned on, the control circuit CC1 controls the output of each voltage during lighting shown in FIG. 13 and supplies power to the discharge lamp DL. Control is performed.

That is, the on / off control of the FET Q31 is performed on the boost chopper circuit 2a as in the start-up. The output voltage level of the step-down chopper circuit 3 is detected, and the on / off of the FET Q31 is controlled so that the detection result becomes the level of the voltage Vb shown in FIG.
Off control is performed.

Further, for the lighting circuit 4f, an FET
On / off control of Q41 to Q44 is performed, and the discharge lamp DL
The DC power from the step-down chopper circuit 3 is converted into AC power so that the discharge of FIG. 10 becomes an arc discharge determined by, for example, the lamp voltage and the lamp current at the point C shown in FIG. That is, the voltage becomes the lamp voltage at the point C, and the current is converted into AC power which becomes the lamp current at the point C. Thus, the discharge lamp DL is stably lit in the state of the arc discharge at the point C, and this lit state is maintained until the power is turned off.

However, if the instantaneous power failure of the AC power supply AC occurs for any reason different from the power-off, a voltage drop due to the instantaneous power failure of the AC power supply AC is detected. When this voltage drop is detected, the FETs Q41 to Q4
4 is performed for a predetermined time, and the DC power from the step-down chopper circuit 3 is supplied with AC power so that the discharge of the discharge lamp DL becomes a glow discharge determined by, for example, the lamp voltage and the lamp current at point A shown in FIG. Converted to electric power. As a result, the discharge lamp DL is stably lit in the state of the glow discharge at the point A. At this time, the amount of power supplied to the discharge lamp DL is smaller than the amount of power at the point C, so that the time during which the discharge lamp DL can be maintained lit by the charging power of the capacitor C21 becomes longer.

Thereafter, the AC power supply AC recovers from the momentary power failure, and when the above-described predetermined time has elapsed, AC power serving as a lamp voltage and a lamp current at point C is supplied to the discharge lamp DL. As a result, the discharge lamp DL quickly returns from the glow discharge state at the point A to the arc discharge state at the point C.

As described above, according to the seventh embodiment, it is possible to prevent extinguishing due to an instantaneous power failure. Further, since it is not necessary to increase the capacity of the capacitor C21 and it is not necessary to make the igniter 40 an instantaneous restart type, it is possible to suppress an increase in the size of the circuit. Thereby, cost increase can be suppressed.

Further, when a so-called standby power supply (compensated power supply) used when the AC power supply AC is out of power is provided, the lighting of the discharge lamp DL is maintained by the charging power of the capacitor C21 until the standby power supply operates. Since the discharge lamp DL does not go out, the discharge lamp DL can quickly shift to arc discharge by the standby power supply.

FIG. 14 is a schematic structural view of a discharge lamp lighting device according to an eighth embodiment of the present invention. The eighth embodiment will be described below with reference to this drawing. A booster chopper circuit 2a, a step-down chopper circuit 3, and a lighting circuit 4f are provided in the same manner as in the seventh embodiment, and a discharge lamp provided on a line on the low potential side between the step-down chopper circuit 3 and the lighting circuit 4f. A current detection circuit (current detection means) 10 for detecting a current value to DL and a control circuit CC2 are provided. However, the boost chopper circuit 2a
From the output voltage of the rectifier DB, it is set to obtain a level above the output voltage of the maximum and becomes the ramp voltage V _G generated between the normal glow discharge and arc discharge shown in FIG. 10. Thereby, the step-down chopper circuit 3 outputs the lamp voltage V
Voltage output above the _G level is possible.

The control circuit CC2 is the same as the control circuit CC1 except that a power reduction section 9g is provided instead of the power reduction section 9f. The power reduction section 9g operates when a voltage drop is detected by the detection section 8b. The lamp current obtained from the detection result of the current detection circuit 10 is the lamp current I shown in FIG.
_The FET Q4 is controlled so as to supply AC power that is equal to or less than _G and becomes, for example, a current ID at a point _D from the lighting circuit 4f to the discharge lamp DL.
On / off control of 1 to Q44 is performed for a predetermined time. However,
At the time of lighting of the arc discharge, the lamp circuit obtained from the detection result of the current detection circuit 10 supplies, for example, the alternating current power which becomes the lamp current at the point C shown in FIG.
Is controlled to turn on / off the FETs Q41 to Q44.

Next, the characteristic operation of the eighth embodiment performed in accordance with the detection result of the detection unit 8b will be described. In a normal state, the lamp current obtained from the detection result of the current detection circuit 10 is shown in FIG. For example, AC power is supplied to the discharge lamp DL so as to have a lamp current at point C. Thus, the discharge lamp DL is stably lit in the state of the arc discharge at the point C, and this lit state is maintained until the power is turned off.

However, if the instantaneous power failure of the AC power supply AC occurs for some reason different from the power-off, a voltage drop due to the instantaneous power failure of the AC power supply AC is detected.
According to this detection result, the ON / OFF of the FETs Q41 to Q44
Off control is performed for a predetermined time, the AC power lamp current becomes a current I _D of the D point shown in FIG. 10 is supplied from the lighting circuit 4f to the discharge lamp DL. As a result, the discharge lamp DL is stably lit in the state of the glow discharge at the point D. At this time, the amount of power supplied to the discharge lamp DL is smaller than the amount of power at the point C, so that the time during which the discharge lamp DL can be maintained lit by the charging power of the capacitor C21 becomes longer.

After that, the AC power supply AC recovers from the momentary power failure, and when the above-mentioned predetermined time has elapsed, power serving as the lamp voltage and the lamp current at the point C is supplied to the discharge lamp DL.
As a result, the discharge lamp DL quickly returns from the glow discharge state at the point A to the arc discharge state at the point C.

As described above, according to the eighth embodiment, it is possible to prevent extinguishing due to an instantaneous power failure. Further, since it is not necessary to increase the capacity of the capacitor C21 and it is not necessary to make the igniter 40 an instantaneous restart type, it is possible to suppress an increase in the size of the circuit. Thereby, cost increase can be suppressed.

[0114]

As is apparent from the above description, according to the first aspect of the present invention, a discharge lamp, a DC power supply including a rectifier that takes in AC power from an AC power supply and performs rectification, a switching element, and an inductance. A lighting circuit comprising an element for supplying power to the discharge lamp using power from the DC power supply; detecting means for detecting a voltage drop caused by stopping power supply from the AC power supply; and a voltage drop by the detecting means. Is detected, a power reduction unit that performs control for reducing the amount of power supplied to the discharge lamp for a predetermined time is provided. become.

According to the second aspect of the present invention, there is provided the chopper circuit which comprises a switching element and an inductance element and converts a voltage level from the rectifier to a predetermined level to supply DC power to the lighting circuit side. In addition, it is possible to prevent extinction due to an instantaneous power failure, to suppress an increase in circuit size, and to suppress an increase in cost.

According to the third aspect of the present invention, when the voltage drop is detected by the detecting means, the power reducing means controls the supply of DC power to reduce the power supply to the discharge lamp for a predetermined time. Therefore, it is possible to prevent extinguishing due to an instantaneous power failure, to suppress an increase in circuit size, and to suppress an increase in cost.

According to the fourth aspect of the present invention, there is provided an igniter for generating a high voltage for starting the discharge lamp, and the power reducing means detects a high voltage of the igniter when the voltage drop is detected by the detecting means. Since the voltage generation control is performed for a predetermined time, it is possible to prevent the extinction from occurring due to an instantaneous power failure, to suppress an increase in circuit size, and to suppress an increase in cost.

According to the fifth aspect of the present invention, the power reduction means stabilizes the discharge lamp by glow discharge for a predetermined time when the voltage drop is detected by the detection means. This makes it possible to prevent such problems, suppress an increase in the size of the circuit, and suppress an increase in cost.

According to the invention of claim 6, there is provided current detecting means for detecting a current flowing through the discharge lamp, and the power reducing means detects the current when the voltage drop is detected by the detecting means. Since the discharge lamp is supplied with power so that the value of the lamp current of the discharge lamp obtained from the detection result of the means is equal to or less than a current value capable of shifting to arc discharge, and the discharge of the discharge lamp is glow discharge, This makes it possible to prevent extinction due to a power failure, to suppress an increase in circuit size, and to suppress an increase in cost.

According to the seventh aspect of the present invention, the power reducing means keeps the lamp current at the time of glow discharge constant.
This makes it possible to prevent extinction due to an instantaneous power failure, to suppress an increase in circuit size, and to suppress an increase in cost.

According to the invention, when the predetermined time has elapsed, the discharge of the discharge lamp is changed from a glow discharge to an arc discharge.
It is possible to suppress an increase in the size of the circuit and an increase in cost.

According to the ninth aspect of the present invention, the discharge lamp has a voltage application capability not less than the maximum value of the lamp voltage generated at the transition between the glow discharge and the arc discharge, and when the predetermined time has elapsed, the discharge lamp Is discharged from the glow discharge to the arc discharge by supplying electric power that is equal to or more than a current value that can be transferred to arc discharge, thereby preventing extinction due to an instantaneous power failure, suppressing increase in circuit size, and cost. It is possible to suppress the up.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a discharge lamp lighting device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of the detection circuit shown in FIG.

FIG. 3 is an explanatory diagram of a control circuit shown in FIG.

FIG. 4 is a schematic configuration diagram of a discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a discharge lamp lighting device according to a third embodiment of the present invention.

FIG. 6 is an explanatory diagram of a control circuit for the lighting circuit shown in FIG. 5;

FIG. 7 is a schematic configuration diagram of a discharge lamp lighting device according to a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a state of a lamp voltage and a lamp current of a discharge lamp according to a fourth embodiment.

FIG. 9 is a schematic configuration diagram of a discharge lamp lighting device according to a fifth embodiment of the present invention.

FIG. 10 is a diagram showing a relationship between a lamp voltage and a lamp current and a discharge state.

FIG. 11 is a schematic configuration diagram of a discharge lamp lighting device according to a sixth embodiment of the present invention.

FIG. 12 is a schematic configuration diagram of a discharge lamp lighting device according to a seventh embodiment of the present invention.

FIG. 13 is an explanatory diagram of the control circuit shown in FIG.

FIG. 14 is a schematic configuration diagram of a discharge lamp lighting device according to an eighth embodiment of the present invention.

FIG. 15 is a schematic configuration diagram showing a conventional discharge lamp lighting device.

[Explanation of symbols]

1, 1a, 1b DC power supply 2, 2a Step-up chopper circuit 3, 3a Step-down chopper circuit 4, 4a, 4c, 4d, 4e, 4f Lighting circuit 5 Control circuit (for step-up chopper circuit) 6, 6a (for step-down chopper circuit) Control circuit 7, 7a, 7b (for lighting circuit) control circuit 8, 8a detection circuit 8b detection section 9, 9a, 9b, 9c, 9d, 9e, 9f, 9g power reduction section 10 current detection circuit CC1, CC2 Control circuit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Jun Kumagai 1048 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Works Co., Ltd. 3K072 AA11 BA03 BA05 BB01 BB10 BC01 DD07 EA05 EB01 EB05 EB07 GA01 GA02 GB12 GB18 GC04 HA10 HB03 5H007 AA04 AA17 BB03 CA01 CA02 CB04 CB12 CC12 DA05 DB01 DC02 DC05 FA02

Claims (9)

[Claims] 1. A discharge lamp, a DC power supply comprising a rectifier for taking in AC power from an AC power supply and performing rectification, and a switching element and an inductance element to supply power to the discharge lamp using power from the DC power supply. A lighting circuit that performs the following operations: a detecting unit that detects a voltage drop due to a stop of the power supply from the AC power supply; and when the detecting unit detects the voltage drop, a control to reduce the amount of power supplied to the discharge lamp is performed. A discharge lamp lighting device comprising: a power reducing unit for performing time. 2. The discharge lamp lighting device according to claim 1, further comprising a chopper circuit comprising a switching element and an inductance element for converting a voltage level from the rectifier to a predetermined level and supplying DC power to the lighting circuit side. . 3. The power reduction unit according to claim 1, wherein, when a voltage drop is detected by the detection unit, supply control of the DC power to reduce the power supply to the discharge lamp is performed for a predetermined time. Discharge lamp lighting device. 4. An igniter for generating a high voltage for starting the discharge lamp, wherein the power reduction means performs high voltage generation control of the igniter for a predetermined time when a voltage drop is detected by the detection means. Item 4. The discharge lamp lighting device according to any one of Items 1 to 3. 5. The discharge lamp lighting device according to claim 1, wherein the power reduction unit stabilizes the discharge lamp by glow discharge for a predetermined time when a voltage drop is detected by the detection unit. 6. A power detection device for detecting a current flowing through the discharge lamp, wherein the power reduction device obtains a voltage drop from the detection result of the current detection device when a voltage drop is detected by the detection device. 6. The discharge lamp lighting device according to claim 5, wherein the discharge lamp is supplied with electric power at which a lamp current value of the discharge lamp is equal to or less than a current value capable of shifting to arc discharge, and discharge of the discharge lamp is glow discharge. 7. The discharge lamp lighting device according to claim 5, wherein said power reducing means keeps a lamp current constant during glow discharge. 8. The discharge of the discharge lamp is changed from a glow discharge to an arc discharge after the predetermined time has elapsed.
The discharge lamp lighting device according to any one of the above. 9. The discharge lamp has a voltage application capability not less than a maximum value of a lamp voltage generated at the time of transition between glow discharge and arc discharge. The discharge lamp lighting device according to any one of claims 5 to 8, wherein electric power having a current value equal to or more than a possible value is supplied to the discharge lamp to change from glow discharge to arc discharge.